Structure and electronic properties of C2N/graphene predicted by first-principles calculations

Abstract

The zero band gap of pristine graphene hinders its application in high-performance field effect transistors (FETs) at room temperature. The symmetry breaking of the sub-lattice, originated from the influence of substrates such as silicon carbide, hexagonal boron nitride as well as graphitic carbon nitride (C₃N₄), can produce a band gap in graphene. Herein, another novel kind of substrate, C₂N, is employed to break the symmetry of the graphene sub-lattice, resulting in a band gap of about 0.40 eV in graphene. In combination with C₂N through the weak van der Waals (vdW) interaction, graphene keeps its structural integrity and charge mobility. A band opening as large as 0.72 eV could be achieved through reducing the layer spacing to 3.2 Å. This is because the amount of electron transfer from graphene to C₂N and the interaction between C₂N and graphene increase with the decreasing interlayer spacing. Moreover, though the band gap of C₂N is slightly altered, its electronic properties especially the direct band gap in visible region and the band dispersions are almost preserved. Thus, our theoretical results predict the promising multifunctional applications of C₂N/graphene (C₂N/G) heterostructures, including high-performance FETs and metal-free photocatalytic materials for water splitting.